From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id 4D389ADF8 for ; Wed, 22 Jun 2016 03:35:56 +0200 (CEST) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP; 21 Jun 2016 18:35:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,507,1459839600"; d="scan'208";a="723115244" Received: from fmsmsx107.amr.corp.intel.com ([10.18.124.205]) by FMSMGA003.fm.intel.com with ESMTP; 21 Jun 2016 18:35:51 -0700 Received: from FMSMSX109.amr.corp.intel.com (10.18.116.9) by fmsmsx107.amr.corp.intel.com (10.18.124.205) with Microsoft SMTP Server (TLS) id 14.3.248.2; Tue, 21 Jun 2016 18:35:50 -0700 Received: from shsmsx103.ccr.corp.intel.com (10.239.4.69) by fmsmsx109.amr.corp.intel.com (10.18.116.9) with Microsoft SMTP Server (TLS) id 14.3.248.2; Tue, 21 Jun 2016 18:35:49 -0700 Received: from shsmsx102.ccr.corp.intel.com ([169.254.2.147]) by SHSMSX103.ccr.corp.intel.com ([169.254.4.181]) with mapi id 14.03.0248.002; Wed, 22 Jun 2016 09:35:38 +0800 From: "Lu, Wenzhuo" To: Jerin Jacob , "Ananyev, Konstantin" CC: Stephen Hemminger , "dev@dpdk.org" , "Richardson, Bruce" , "Chen, Jing D" , "Liang, Cunming" , "Wu, Jingjing" , "Zhang, Helin" , "thomas.monjalon@6wind.com" Thread-Topic: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device reset Thread-Index: AQHRyrx6NqZsK6LoQ0Kr0EDRoXtySZ/xjKGAgAB2MwCAAMH0gIAAqwkw//+UC4CAAIsykP//irIAgAAIkQCAABmdAIAAJRoAgAAFmQCAAAkYgIAAB1CAgAE5dBA= Date: Wed, 22 Jun 2016 01:35:37 +0000 Message-ID: <6A0DE07E22DDAD4C9103DF62FEBC09090348971F@shsmsx102.ccr.corp.intel.com> References: <20160621035124.GC4903@localhost.localdomain> <6A0DE07E22DDAD4C9103DF62FEBC090903488DD1@shsmsx102.ccr.corp.intel.com> <20160621073710.GA30638@localhost.localdomain> <6A0DE07E22DDAD4C9103DF62FEBC090903488F5E@shsmsx102.ccr.corp.intel.com> <20160621085531.GA31880@localhost.localdomain> <2601191342CEEE43887BDE71AB97725836B73FD0@irsmsx105.ger.corp.intel.com> <20160621105751.GA737@localhost.localdomain> <2601191342CEEE43887BDE71AB97725836B74226@irsmsx105.ger.corp.intel.com> <20160621133041.GA7509@localhost.localdomain> <2601191342CEEE43887BDE71AB97725836B7433B@irsmsx105.ger.corp.intel.com> <20160621142924.GA8670@localhost.localdomain> In-Reply-To: <20160621142924.GA8670@localhost.localdomain> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device reset X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Jun 2016 01:35:56 -0000 Hi Jerin, > -----Original Message----- > From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com] > Sent: Tuesday, June 21, 2016 10:29 PM > To: Ananyev, Konstantin > Cc: Lu, Wenzhuo; Stephen Hemminger; dev@dpdk.org; Richardson, Bruce; Chen= , > Jing D; Liang, Cunming; Wu, Jingjing; Zhang, Helin; > thomas.monjalon@6wind.com > Subject: Re: [dpdk-dev] [PATCH v6 1/4] lib/librte_ether: support device r= eset >=20 > On Tue, Jun 21, 2016 at 02:03:15PM +0000, Ananyev, Konstantin wrote: > > > > > > > > > > > Hi Wenzhuo, > > > > > > > > > > > > > > > > > > > > On Mon, Jun 20, 2016 at 02:24:27PM +0800, Wenzhuo= Lu > wrote: > > > > > > > > > > > > > > Add an API to reset the device. > > > > > > > > > > > > > > It's for VF device in this scenario, kernel PF = + DPDK VF. > > > > > > > > > > > > > > When the PF port down->up, APP should call > > > > > > > > > > > > > > this API to reset VF port. Most likely, APP > > > > > > > > > > > > > > should call it in its management thread and > > > > > > > > > > > > > > guarantee the thread safe. It means APP should > > > > > > > > > > > > > > stop the rx/tx and the device, then reset the d= evice, then > recover the device and rx/tx. > > > > > > > > > > > > > > > > > > > > > > > > > > Following is _a_ use-case for Device reset. But > > > > > > > > > > > > > may be not be _the_ use case. IMO, We need to > > > > > > > > > > > > > first say expected behavior of this API and add a= use-case > later. > > > > > > > > > > > > > > > > > > > > > > > > > > Other use-case would be, PCIe VF with functional > > > > > > > > > > > > > level reset for SRIOV migration. > > > > > > > > > > > > > Are we on same page? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > In my experience with Linux devices, this is > > > > > > > > > > > > normally handled by the device driver in the start > > > > > > > > > > > > routine. Since any use case which needs this is > > > > > > > > > > > > going to do a stop/reset/start sequence, why not ju= st have > the VF device driver do this in the start routine?. > > > > > > > > > > > > > > > > > > > > > > > > Adding yet another API and state transistion if > > > > > > > > > > > > not necessary increases the complexity and required= test > cases for all devices. > > > > > > > > > > > > > > > > > > > > > > I agree with Stephen here.I think if application > > > > > > > > > > > needs to call start after the device reset then we > > > > > > > > > > > could add this logic in start itself rather exposing > > > > > > > > > > > a yet another API > > > > > > > > > > Do you mean changing the device_start to include all > > > > > > > > > > these actions, stop > > > > > > > > > device -> stop queue -> re-setup queue -> start queue -> = start > device ? > > > > > > > > > > > > > > > > > > What was the expected API call sequence when you were > introduced this API? > > > > > > > > > > > > > > > > > > Point was to have implicit device reset in the API call > > > > > > > > > sequence(Wherever make sense for specific PMD) > > > > > > > > I think the API call sequence depends on the > > > > > > > > implementation of the APP. Let's say if there's not this > > > > > > > > reset API, APP can use > > > this > > > > > API > > > > > > > call sequence to handle the PF link down/up event, > > > > > > > rte_eth_dev_close -> rte_eth_rx_queue_setup -> > > > rte_eth_tx_queue_setup - > > > > > > > > > > > > > rte_eth_dev_start. > > > > > > > > Actually our purpose is to use this reset API instead of > > > > > > > > the API call sequence. You can see the reset API is not > > > > > > > > necessary. The > > > > > benefit > > > > > > > is to save the code for APP. > > > > > > > > > > > > > > Then I am bit confused with original commit log description. > > > > > > > | > > > > > > > |It means APP should stop the rx/tx and the device, then > > > > > > > |reset the device, then recover the device and rx/tx. > > > > > > > | > > > > > > > I was under impression that it a low level reset API for > > > > > > > this device? Is n't it? > > > > > > > > > > > > > > The other issue is generalized outlook of the API, Certain > > > > > > > PMD will not have PF link down/up event? Link down/up and > > > > > > > only connected to VF and PF only for configuration. > > > > > > > > > > > > > > How about fixing it more transparently in PMD driver itself > > > > > > > as PMD driver knows the PF link up/down event, Is it > > > > > > > possible to recover the VF on that event if its only matter o= f resetting > it? > > > > > > > > > > > > I think we already went through that discussion on the list. > > > > > > Unfortunately with current dpdk design it is hardly possible. > > > > > > To achieve that we need to introduce some sort of > > > > > > synchronisation between IO and control APIs (locking or so). > > > > > > Actually I am not sure why having a special reset function will= be a > problem. > > > > > > > > > > | > > > > > |It means APP should stop the rx/tx and the device, then reset > > > > > |the device, then recover the device and rx/tx. > > > > > | > > > > > Just to understand, If application still need to do the stop > > > > > then what value addtion reset API brings on the table? > > > > > > > > If application calls dev_reset() it doesn't need to call dev_stop()= before it. > > > > dev_reset() will take care of it. > > > > But it needs to make sure that no other thread will try to modify > > > > that device state (either dev_stop/start, or eth_rx_busrst/eth_tx_b= urst) > while the reset op is in place. > > > > > > OK. This description looks different than commit log and API doxygen > comment. Please fix it. > > > How about a different name for this API. Device reset is too generic? Any suggestion? I use this name because I believe what this API do is to re= set the device. > > > > > > > > > > > > > > > > > > > > > > > Yes, it would exist only for VFs, for PF it could be left unimp= lemented. > > > > > > Though it definitely seems more convenient from user point of > > > > > > view, they would know: to handle VF reset event, they just > > > > > > need to call that particular function, not to re-implement thei= r own. > > > > > What if driver returns "not implemented" then application will > > > > >have do generic rte_eth_dev_stop/rte_eth_dev_start. > > > > >That way in application perspective we are NOT solving any proble= m. > > > > > > > > True, but as I said for PF application would just never receive suc= h event. > > > What is this event ? Is it VF Link up/down event? > > > > > > No I was referring to VF itself, Other VF PMD drivers in drivers/net > > > where this callback is not implemented. > > > > Hmm, the only suggestion I have here - Maintainers/developers of > > non-Intel PMD will implement it for their VFs? >=20 > That's fine. But, We have to know what to implement here in PMD perspecti= ve? > That's reason being asking about the API expectation and application usag= e :-) >=20 > > In case of course they do need to handle similar event. > Which is this event and How application get notify it. When the PF link is down/up, the PF will use the mailbox to send a message = to VF. The event here means the VF receives that message from PF. So VF can= know the physical link state changed. You see it's only for VF. PF will no= t receive such kind of message. And we use the callback mechanism to let APP notified. APP should register = a callback function. When VF driver receives the message it will call the c= allback function, then APP can know that. >=20 > > if not I suppose there is no harm to left it unimplemented. > OK. If it is for VF/PF link down-up event then I will make it as 'nop'. As explained above, the event is not VF/PF link down-up. Actually it's that= VF is notified the PF link is down-up. And to my opinion, although now we only implement the reset API for VF, I b= elieve there's nothing preventing us to implement this API for PF if we can= find some scenario that we need to reset the PF link. The reset API is res= et API, it can be used for the event described above. But it's not bound to= this event. >=20 > Jerin >=20 > > Konstantin > >